2022–2023 mpox outbreak in France

Mpox (formerly known as monkeypox)[2] is an infectious viral disease that can occur in humans and some other animals.[3] Symptoms include a rash that forms blisters and then crusts over, fever, and swollen lymph nodes.[3] The time from exposure to onset of symptoms ranges from five to twenty-one days and symptoms typically last from two to four weeks.[4][5] There may be mild symptoms, and it may occur without any symptoms being apparent.[4][6] Cases may be severe, especially in children, pregnant women or people with suppressed immune systems.[7]

The disease is caused by the monkeypox virus,[lower-alpha 1] a zoonotic virus in the genus Orthopoxvirus.[8] The variola virus, the causative agent of smallpox, is also in this genus.[9] It may spread from infected animals by handling infected meat or via bites or scratches.[10] Human-to-human transmission can occur through exposure to infected body fluids or contaminated objects, by small droplets, and possibly through the airborne route.[3][10] People can spread the virus from the onset of symptoms until all the lesions have scabbed and fallen off; with some evidence of spread for more than a week after lesions have crusted.[11] Diagnosis can be confirmed by testing a lesion for the virus's DNA.[12]

There is no known cure.[13] A study in 1988 found that the smallpox vaccine was around 85% protective in preventing infection in close contacts and in lessening the severity of the disease.[14] A newer smallpox and mpox vaccine based on modified vaccinia Ankara has been approved, but with limited availability.[4] Other measures include regular hand washing and avoiding sick people and animals.[15] Antiviral drugs, cidofovir and tecovirimat, vaccinia immune globulin and the smallpox vaccine may be used during outbreaks.[16][17] The illness is usually mild and most of those infected will recover within a few weeks without treatment.[17] Estimates of the risk of death vary from 1% to 10%, although few deaths as a consequence of mpox have been recorded since 2017.[18]

An ongoing outbreak of mpox was confirmed on 6 May 2022, beginning with a British resident who, after travelling to Nigeria (where the disease is endemic), presented symptoms consistent with mpox on 29 April 2022. The resident returned to the United Kingdom on 4 May, creating the country's index case of the outbreak.[19] The origin of several of the cases of mpox in the United Kingdom is unknown. Some monitors saw community transmission taking place in the London area as of mid-May,[20] but it has been suggested that cases were already spreading in Europe in the previous months.[21]